Inlay-casting machine.



F. H. NIBS.

INLAY CASTING MACHINE. APPLIOATION FILED MAB..3,1910.

Patented Sept. 26, 1911.

Fig. 4.

-WITNESSES: ti e...

illustrated the flask in which ceipt of the molten gold.

I To all/whom it citizenof the United UNITED sTA Es PATENT OFFICE.

FREDERICK H. NIES, OF NEW YORK, N. Y.

INLAY-CASTING MACHINE.

Specification of Letterslatent. Application filed March 3, 1910. Serial No.

may concern: known that I, Fnnnnniou H. Nins, a Status, residing in the borough of Brooklyn, colmty of Kings, city and State of New York, have invented con tain new and useful In'iprovcmcnts .in Inlay- Casting Machines, of which the following is a specification.

In the casting of inlays of gold or other material for dental fork there are sometimes losses of castings or failures, the cause of which is not clear. According to this invention the casting is effected in such a way as to practically eliminate such losses or failures, or atleast to reduce them to a minimum. \Vhile there may be other causes which contlibute at different times, or sev- Be it oral causes. at one time, to the losses or fail arcs of the castings, I have discovered that. a cause of many such losses or failures is the escape of a. large part of the pressure which is depended upon to force the molten gold into the mold.

The principal features of my invention are concerned with the prevention of such losses of pressure and the generation of a large supply of pressure fluid.

he accompanying drawings illustrate the use of an apparatus according to the invention.

l igure 1 is a perspective view of the parts of the apparatus used in 'inaking the mold. Fig. 2 is a sectional view"'of the same with the investment material of which the mold is composed cast in place. Fig. 3 is a sectional view of the parts in the position for the casting of the inlay. Fig. -:t. is a sectional view showing the actual casting operation. Fig. 5 is a plan of a su 'iplementary heating element.

Referring to the form of the apparatus the mold is made comprises a base A and one or more rings B of suitable sizes adapted to rest endwise on the base. The base is provided at the center with an inwardly projecting por tion (3- for forming a hollow in what is evcntually the top of the mold for'the rc- An impression of the cavity of tbetooth is taken with wax or other suitable material, as indicated at D. This wax in'ipression is then mounted on theend. of th.e;pin E which fits into asmall hole in the base. A quill F is introduced about the part of the pin E which is adja cent to the impression piece D so as to hold the latter at the proper height and to form Patented Sept. 26, 1911. 547,068.

in the investment material a sutliciently large sprue or gate. The impression .piece and the flask, being properly positioned, as in Fig. 2, the investment material is poured in the top to nearly or approximately fill the flask. Various compositions are in use as investment: materials. A good example is plaster of Paris, two parts, French chalk, two parts, and Portland cement, one-half part. When this flask ring is removed from its base and the pin is witlu'lrawn. The flask ring. with the investment material therein, and the impression piece, are then heated. impression piece is melted out leaving an exact mold of the inlay. The investment material should be thoroughly heated to make it porous so that it will permit dispersion of the air in the mold when the molten gold is that it should not chill the molten gold as the latter passes through the sprue into the mold cavity; and so as to avoid the subsequent formation of steam in the investment material which, forcing its way out through the sprue, would retard the entrance of the molten metal and cause the formation of imperfect edges. Generally speaking, within the limit of such heat as might fuse the investment material themold should be very thoroughly and uniformly heated and the casting should be made while the mold is very hot. This heating and drmving out of the investment material causes a substantial shrinkage thereof. Likewise the heatin; causes a substantial expansion of the ask ring which is ordinarily of metal. Thus there is a space not always perceptible to the eye formed between the investment material and the flask ring. Then when pressure is introduced-to force the molten metal into the mold the pressure is liable to be dissipated to a substantial extent through the space between the investment material and the flask ring.

. way is by means of a so-called pressure plunger II having a face J of asbestos or other The wax" has had time to set the fibrous fireproof material. This fibrous face is wet and brought down by hand upon the upper edge of the fiasl. The heat of the flask, the molten gold, and the hot invest- .the time), as in Fig.

ring, and to force. themolten gold into the mold. The quantity of steamis limited and with such an a ')paratns it is especially important to take precautions against. the loss of any of the pressure fluid,

According to one feature of my invention thespace formed by heating between the investment material and the flask ring is so tightly closed as to substantially orcvent any escape of pressure by this way. arious means may be provided for this purpose. The simplest is probably that illustrated in which the inner portion K of the flask ring is tapered, the smaller diameter being preferably at the lower end (calling the end through which the gold isintroduced the upper end). In using such a ring the investment mate 'ial is introduced so that it comes nearly to the bottom edge of the flask ring (which is uppermost at After thorough drying and heating a space will be left which is indicated by a heavy line in Fig. 3 and the investment material may be pushed so tightly into the ring that any air, gas or i steam or other pressure fluid will be etlectually prevented from escaping between the rifl and the investment when the castin is O :1

made, as in Fig. at. This close fit oi the investn'ient in the ring also altords stability and support for the former and prevents it from being split asunder by too great a pres sure in casting as is sometimes the case with apparatus of prc\-'ious styles. This is especially true in making large castings, in which case the investment material needs to be supported firmly on all sides to prevent its being broken to pieces. The coi'iserving of the pressure by closing the space between themvestment material and the ring makes very much easier the-casting of full plates, wh ch must be thin and light cnonghto be Worn, and the casting of which would. otherwise be a di'llicult tast; and this conserving of the pressure also secures hater castings with sharper and more perfect faces and edges than can be secured in the old. way.

The invention is a pplicalflc not to merely the casting of inlays for single teeth, but also to the various analogous operations required in dentistry, such as the casting oi plates or pieces of gold, aluminum or other materials.

An. additional, feature which I have invented relates to the generation of pressure in increased quantity as compared with previous methods. This is done by providing an a'dditional heating element to act upon the wet pad. With previous apparatus the asbestos pad has been. brought down so that it contacted only with the comparatively narrow edge of the flask ring and received the greater part of its heat by this contact. I propose to provide within the ring an additional heating element preferably consisting of a metal ring or coil L shown separately in Fig. 5, and which is of a suitable size to be placed easily in the. top of the ring upon the edge of the investment material so as to till the space between the latter and the steam genera-ting pad, and to heat the latter by direct contact. .It is not safe to permit the investmentmaterial to come into contact with the comparatively cold pad (even where it has been heated with hot water because the one ual contraction caused by the sudden chilling of the investment will sometimes crack it. Nor is it advisable to allow the molten nugget to give up its heat for the generating of steam. The use of the additional heating element tends to save the investment material and the nugget from these objectionable incidents. The heating element L should be placed on top of the investment as soon as the gold is softened, all the parts being then heated together, ordinarily with the metal into the mold, and an additional heat-Q ing ele ment adapted to increase the heating surface in contact with the pad.

2. An inlay casting apparatus including a flask ring adapted to receive the investment material, a pad adapted to be moistened and brought down upon the edge of said rin to generate steam for pressing the metal into the mold, and an additiona-l heating element conniirising a metallic ring-shaped piece fitting within the edge of the flask ring and adapted to rest upon. the investment material and to come into contact with the pad when the latter is brought down, to increase the stoma-generating surface.

In witness whereof, I have hereunto signed v my name in the presence of two subscribing witnesses.

FREDERICK H NIES.

Witnesses:

D. An'rnoNY UsINA, Flinn WHITE. 

